Cephalosporins have widely been utilized as antibiotics for mammals including humans. Various studies have extensively been made in this technical field for the purpose of intensifying the effectiveness and the safety of the cephalosporin antibiotics, and the outlines are described say in "Penicillin and Cephalosporin" (written by Edwin H. Flynn and published by Academic Press Co., in 1972) or "Structure Activity Relationships among the semisynthetic Antibiotics" (written by D. Perlman and published by Academic Press Co., in 1977). According to the disclosure of these publications, various kinds of cephalosporin-type compounds having an increased anti bacterial activity may be obtained by introducing various kinds of substitutes in the 7-acyl group or 3-substituent in the compounds.
For example, the introduction of an acyl group as derived from an .alpha.-alkoxyiminoaminothiazoleacetic acid into the 7-position of cephalosporin compounds has been noticed in these years, and U.S. Pat. Nos. 4,098,888 and 4,166,115 and British Patent No. 2,022,090 describe compounds having a residue derived from an .alpha.-methoxyiminoaminothiazoleacetic acid, and in addition, German Patent No. 2,921,316 describes compounds having a residue derived from an .alpha.-dimethylcarbomethoxyiminoaminothiazoleacetic acid. Thus, various studies have widely been made in this technical field to vary the part of the alkoxy-substituent in the .alpha.-alkoxyimino part of the aminothiazoleacetic acid residue in the cephalosporin compounds.
On the other hand, the introduction of residues of various kinds of heterocyclic compounds in the 3-positioned substituent of cephalosporin compounds has heretofore been tried. However, there are only some few compounds into which a pyridinium quaternary salt residue is introduced via a sulfur atom in the form of a 1-alkylpyridinium-4-ylthiomethyl group, and Japanese Patent Application OPI No. 90590/83 and No. 89289/80 describes some of these compounds. (The term "OPI" as used herein means an "unexamined published application"). These compounds are insufficient in the anti-bacterial activity and have some problems in the actual and practical use thereof. In order to solve the problem of the compounds in the practical use, the present inventors have prepared new cephalosporin compounds having a 1-fluoroethylpyridinium-4-ylthiomethyl group in the 3-position and have already filed a prior patent application of Japanese Patent Application. No. 254517/84. Afterwards, the present inventors have further made various studies on the point of the stereochemical configuration of the alkoxyimino part in the 7-side position of the cephem nucleus of the cephalosporin compounds and have found new compounds having an improved anti bacterial activity against antibiotic-resistant bacteria and having an increased practical usability, and thus have solved the problems now in question.